Rescue Breathing May Not Be Needed for Adult CPR

Action Points

Explain to interested patients that for cardiac arrest that occurs outside the hospital, CPR with chest compressions only provided better survival than CPR with compressions and rescue breathing.

Note that the CPR studied was dispatcher-assisted, which possibly led to the CPR being more effective in maintaining coronary artery perfusion.

For adult patients who have suffered an out-of-hospital cardiac arrest, rescue breathing may not be a crucial component of cardiopulmonary resuscitation (CPR) delivered by a bystander, a meta-analysis showed.

In a pooled analysis of three studies comparing dispatcher-assisted CPR with and without mouth-to-mouth ventilation, using chest compressions alone was associated with a 22% relative increase in survival (risk ratio 1.22, 95% CI 1.01 to 1.46), according to Peter Nagele, MD, of Washington University School of Medicine in St. Louis, and colleagues.

The absolute increase in survival was 2.4% (from 12% to 14%), with a number needed to treat of 41 (95% CI 20 to 1250), they reported online in The Lancet.

"Our findings support the idea that emergency medical services dispatch should instruct bystanders to focus on chest-compression-only CPR in adults with out-of-hospital cardiac arrest," Nagele and his colleagues wrote. "However, whether chest-compression-only CPR should be recommended for unassisted lay bystander CPR is unclear."

U.S. and European guidelines for standard basic life support, last updated in 2005, recommend standard CPR combining chest compressions and rescue ventilation at a ratio of 30 compressions for every two breaths.

But the usefulness of rescue breathing has been questioned for certain patients, including adults with out-of-hospital cardiac arrest with suspected cardiac origin, as opposed to that related to asphyxia or trauma.

Only three randomized trials have explored the issue, and each identified a nonsignificant survival advantage with chest compressions alone when CPR was delivered by a bystander with instructions from a dispatcher. Statistical significance probably was not reached because of inadequate statistical power, according to Nagele and his colleagues.

When the results were pooled for the current meta-analysis, however, the benefits became significant.

A secondary meta-analysis of seven observational cohort studies looking at CPR with and without rescue breathing failed to demonstrate a difference between the two techniques; survival was 8% in each group.

Nagele and his colleagues noted in their paper, however, that the CPR in the observational studies was not guided with instructions by a dispatcher.

High-quality compressions are integral to successful CPR, and by not taking the time to perform mouth-to-mouth, "a continuous uninterrupted coronary perfusion pressure is maintained, which increases the probability of a successful outcome," the researchers wrote.

That, they noted, was the main reason the 2005 guidelines from both the U.S. and European societies doubled the compression-to-ventilation ratio for standard basic life support from 15:2 to 30:2.

Compression-only CPR also has the advantage of being easier to teach, learn, and perform. It avoids mouth-to-mouth resuscitation, which many people are hesitant to do, the researchers wrote.

But rescue breathing may be appropriate in some circumstances.

Nagele and his colleagues explained that studies have shown a benefit of mouth-to-mouth ventilation in cases of cardiac arrest from noncardiac causes, such as drowning, trauma, and asphyxia, and also in pediatric cases, which often are due to a primary respiratory arrest and not cardiac in origin.

In an accompanying editorial, Jerry Nolan, MBChB, of the Royal United Hospital NHS Trust in Bath, England, and Jasmeet Soar, MBBChir, of Southmead Hospital in Bristol, England, agreed with Nagele and his colleagues that in cases of adult out-of-hospital cardiac arrest in which the dispatcher determines a cardiac cause is likely, chest compressions alone should be encouraged.

The course of action is less clear for cases in which the bystander is not assisted by a dispatcher, however.

"A bystander who starts CPR will not know how long the emergency medical services will take to arrive, and will not understand the difference between asphyxial and primary cardiac arrest," Nolan and Soar wrote. "Therefore, ideally, lay people should continue to be trained in standard CPR."

"But," they concluded, "any CPR is better than no CPR. Compression-only CPR has an important role in increasing the rate of bystander CPR by those who are untrained, who have only a minimum time for training, or who are unwilling or unable to provide rescue breathing."

Nagele is supported by grants from the National Institute of General Medical Sciences and from the American Heart Association. His institution has received research support unrelated to this study from Roche Diagnostics. He has received consultancy fees from Gerson Lehrman Group. He and his institution have received grants from the NIH and AHA.

Nolan is co-chair of the International Liaison Committee on Resuscitation and editor-in-chief of Resuscitation. Soar is chairman of the U.K. Resuscitation Council and an editor of Resuscitation.

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